Require Guard is a library for Node.js that prevents files from being required and loaded more than once.

When you find yourself fighting code-reloaders or test runners like Mocha to stop reloading your slow initialization code each cycle, and no one else can help, maybe you can hire the Require Guard.

"Hey, but doesn't Node.js' require itself not require files twice?"
Yes, but those pesky code-reloaders and test runners, for your own good, unload everything between [test] cycles to keep things fresh. For such cases Require Guard is the sliced bread beneath your toast. Run that external process or slow op once and not worry that it gets run again.

As an example, let's say you're using Mocha with Selenium WebDriver. Because Selenium starts up as fast as an old Lada engine, you'll want to boot it up once when starting Mocha's watcher and then get on your merry way with testing.

./test/browser.js:

require("require-guard")()

var WebDriver =require("selenium-webdriver")

module.exports =newWebDriver.Builder().build()

./test/test.js:

var browser =require("./browser")

describe("The Internet",function(){...})

Then, while mocha --watch reruns and reruns your tests, your browser will remain open and will get reused.